I. Field of the Invention
The present invention relates to the field of ophthalmic microkeratomes and, more particularly, to microkeratome cutting head assemblies for cutting a corneal flap to prepare a patient""s eye for refractive surgery.
II. Description of the Related Art
The use of microkeratomes in creating a corneal flap for preparing an eye for refractive surgery such as laser-assisted instuikeratomileusis (LASIK) are well known. Typically, a microkeratome cuts a flap of corneal tissue by movement of a blade (either oscillating or non-oscillating) across a cornea of a patient""s eye. The movement of the blade against the cornea typically stops before the corneal flap becomes detached from the cornea. Such microkeratomes are well known and their movement may be arcuate, as described in U.S. Pat. No. 5,624,456, titled Automatic Surgical Device For Cutting a Cornea, by Johann Hellenkamp which is incorporated herein by reference. However, a microkeratome may also translate a blade across the cornea in a linear straight-line fashion which is well-known in the art.
It is common for known microkeratomes to applanate, or flatten-out, the cornea of patient""s eye before the cutting blade of the microkeratome begins to create the flap. This applanation causes the cornea to form a flat surface so that the flat blade may create a proper thickness of cut in the cornea and provide a surgeon with a properly sized flap thickness and diameter.
What has not been appreciated until now is the relationship between a cutting blade""s forward cutting edge and the trailing portion of an applanation member of a microkeratome cutting head assembly. When forming a corneal flap, it is important to prevent damage to the greatest extent possible to the thin epithelial layer of the cornea. Any damage to the epithelial layer of the cornea can cause discomfort and temporarily diminish sight of a patient. In this regard, it is believed that if the forward cutting edge is not positioned properly with respect to the trailing portion of the applanation member, compression of the corneal flap can occur resulting in damage to the epithelial layer of the created corneal flap.
Therefore, there is a need to ensure that compression of the created corneal flap is reduced to minimize potential epithelial damage to the corneal flap.